Write the expression using an exponent:

The number of coins Jada will have on the eighth day if Jada starts with one coin and the number of coins doubles every day. (She has two coins on the first day of the doubling.)

The first one, i believe, would be correct. all the others have one thing in common, and that's that they have repeating numbers. in the second one, x and y have repeating 6's and 3's, and in the third, x and y have repeating 6's as well. in the last one, there are repeating 3's. the first one has no repeating numbers.

Here, feel free to ask if there are any questions